There are three basic directions for such claims--though these are not exclusive interpretations and in fact may reinforce each other.

1. Scholars focus on the character of the colonial state and its institutions, and how its structures were reproduced in postcolonial African states, substantially in the process of decolonization. One of the clearest analyses of this process is still Mahmood Mamdani's book Citizen and Subject, which argued that modes of "indirect rule" in British, French, Belgian and Portuguese administrations created a kind of "decentralized despotism" and a "bifurcated state" that was reproduced in postcolonial governments. Mamdani points out that European administrators divided authority within their possessions in to "customary" and "modern" domains, associating the customary with rural areas and people imagined as 'tribal' subjects; the 'modern' was reserved for urban areas controlled directly by European administrators. The real complexities of existing identities--in many places, people spoke multiple languages, had kinship and residential ties to multiple ethnicities or groups, and were mobile between communities--were suppressed in favor of restrictions on movement and constraining people to a single essentialized 'tribe'. Indirect rule allowed European rulers to underdevelop or simply ignore the common administrative responsibilities of modern states wherever that was too expensive or inconvenient, in particular with regards to education, which they either suppressed altogether or left to missionaries. Africans who gained access to education and were capable of participating in 'modern' administration were constrained to low-level clerking or teaching jobs and were often highly restricted in terms of residential opportunities. Colonial states invested next to nothing in health care, in civic life, etc.

Postcolonial African states were thus left with little prior basis for an overarching idea of national identity and inherited instead the division of political authority that saw the 'customary' as rural, 'tribal' and separate from national administration. They were also left with administrative structures whose primary function was to suppress the growth of civil society, to squash possible dissent, to constrain movement, and to reserve most power for a very small handful of alien outsiders. Decolonization processes consistently blocked off alternative ways of thinking about the structures of rule that postcolonial states might adopt and handed over most administrative structures and processes in the form that they took in the later decades of imperial rule. After that transition, the possibility of radical reorganization of administrative power and territorial allocation in most postcolonial states was effectively foreclosed, and there we sit.

To give you some sense of what this might be like outside of sub-Saharan Africa, imagine if the basis of federalism in the United States was not a Constitution that reserved some forms of sovereign authority to states which were themselves also democratically governed, where the federal government was the guarantor of a number of universal rights and allowed free mobility within the entire nation, but instead was that each of the fifty states was a "customary" domain where unelected 'traditional' authorities had considerable if not fully documented forms of authority; imagine if people of 'Kansas' or 'Massachusetts' were considered to be an unchanging 'ethnicity' who had fixed if informal rights of residence there but who were also not able to move at will into another 'state' with a different customary identity. Imagine also if all administrative histories of this different nation envisioned the political elites as being not merely elites, but essentially belonging almost to another 'tribe' with a completely different (and almost openly) exploitative character.

The colonial state was built for dominating people that it saw as alien and inferior. That was never really undone in the decolonization process.

2. Similarly, in economic terms, most of what colonial states built, they built to facilitate the extraction of resources that were to be used in manufacture elsewhere. The infrastructure was extractive--roads and rail-lines from mines and plantations straight to ports. Land was owned either by foreign corporations or it belonged to the state. Entrepreneurial activity by Africans was discouraged or outright suppressed--in a number of colonial states, for example, Africans growing the same crops as European-owned concerns were forced to sell to state-owned boards or marketing organizations who paid less than the European-owned concerns were able to make on the open market. So again, at independence, African states inherited economies that had little internal diversity, minimal structures for raising local revenues, and that were essentially 'corrupt' in the sense that they funnelled wealth to outsiders and to top-level administrative authorities. The kinds of institutions and policies that create wealth in other states didn't exist, and given the pressing needs that most postcolonial states inherited at independence--to create from scratch health care, education, civic infrastructure, etc.--most of the new rulers felt a need to desperately hold on to what they had or to beg for scraps from the Cold War powers that might let them build what they did not have. Here at least many postcolonial rulers had some pretty dramatic ideas about how to get out of their dilemma, and some of those turned out to make things even worse; in other cases, economic situations were improving until the global economic turmoil of the early 1970s, which then undercut most of the newly independent states.

3. Similarly, in cultural terms, colonial subjects were told for fifty or more years that their own cultures had no history, no worthy art or practices of value, no philosophical insights, no religious practices worthy of respect and so on. Where education was allowed, it was carried out by missionaries from Europe who taught in European languages and who valued only European ideas and achievements. It may sound easy to simply overturn this instantly upon independence, but for a whole host of reasons it was in fact difficult. (Again, to use the example of the United States, it actually took almost a century after independence for Americans to stop slavishly deferring to European culture in most respects.) This created a lasting crisis of dependence upon outside ideas, outside standards of value and worth, and a kind of consequent inferiority complex that has persistent, sometimes subtle, impact on many sub-Saharan Africans.